PHP Visitor Counter Without Database

<?php

/*-----------------------------------------------------------
| @Visitor Counter without using database
| github: https://gist.github.com/RahulSaini91/a09c8f8e6cebf4c66e227699f5860df3
| Save visiter number in cookies
|
| Access the visitor count
| echo the_counter();
| 
| Get it into a variable
| $visitor_num = the_counter()
*/



session_start(); error_reporting(0);


$file_name = 'count'; // set the file location and name to save counting numbers
$use_cookie = 1;
 
//print the visitor counter number
echo the_counter();

/*------------------------------------------------------
| @read file if exists and return the content of file
 -------------------------------------------------------*/
function read_file($file){
    if(file_exists($file)){
        $f = fopen($file,'r');
        $f = fread($f,filesize($file));
        fclose($f);
        return $f;
    }
}
/*-------------------------------------------------------------
| @write the file by using overwrite method if file exists
 --------------------------------------------------------------*/
function write_file($file,$data){
    $f = fopen($file,'w');
    $s = fwrite($f,$data);
    fclose($f);
    return $s;
}
/*-------------------------------------------------------------
| @return the counter number and increase the counter
| @Using session to save current visitor counter
 --------------------------------------------------------------*/
function the_counter(){
    global $file_name;
    if(empty($file_name)){
        return;
    }
    if($_SESSION['counter_number'] > 0 && $use_cookie == 1){
        return $_SESSION['counter_number'];
    }
    $c = read_file($file_name);
    if(empty($c)){
        $c = 0;
    }
    $c = $c+1;
    write_file($file_name,$c);
    $_SESSION['counter_number'] = $c;
    return $c;
}